Comparison of cytotoxicity of pristine and covalently functionalized multi-walled carbon nanotubes in RAW 264.7 macrophages

Carbon nanotubes may be applied in different fields including biomedicine and mechanical engineering. It is important to understand the potential hazards of carbon nanotubes. In the present study, the toxicological effects of the pristine multi-walled carbon nanotubes (p-MWCNTs) and taurine functionalized multi-walled carbon nanotubes (tau-MWCNTs) were assessed on RAW 264.7 macrophages. We tested cell viability, GSH/GSSG ratio, apoptosis, intracellular calcium concentration, ultrastructural changes of cell morphology, and the release of IL-8. We observed the loss of cell viability, decline in the cellular GSH/GSSG ratio, increase of IL-8, and the increase of intracellular calcium concentration in RAW 264.7 macrophages when exposed to p-MWCNTs at high dosage. Additionally, exposure to p-MWCNTs resulted in ultrastructural and morphological changes in RAW 264.7 macrophages. In contrast, the RAW 264.7 macrophages exposed to the tau-MWCNTs did not exhibit altered morphology. Our results conclude that the tau-MWCNTs show lower toxicity than that of p-MWCNTs.     

Multi-walled carbon nanotubes and metallic nanoparticles and their application in biomedicine

Interdisciplinary research has become a matter of paramount importance for novel applications of nanomaterials in biology and medicine. As such, many disciplines-physics, chemistry, microbiology, cell biology, and material science-all contribute to the design, synthesis and fabrication of functional and biocompatible devices at the nanometer scale. Since the most areas of cell biology and biomedicine deal with functional entities such as DNA and proteins, mimicry of these structures and function in the nanosize range offers exciting opportunities for the development of biosensors, biochips, and bioplatforms. In this report we highlight the potential benefits and challenges that arise in the manufacture of biocompatible nanoparticles and nano-networks that can be coupled with biological objects. Among the challenges facing us are those concerned with making the necessary advances in enabling affordability, innovation, and quality of manufactured nanodevices for rapid progress in the emerging field of bio-nanotechnology. The convergence of nanotechnology and biomedicine makes nanoscale research highly promising for new discoveries that can cost-effectively accelerate progress in moving from basic research to practical prototypes and products.     

Hydrogen storage in carbon nanotubes through the formation of stable C-H bonds

To determine if carbon-based materials can be used for hydrogen storage, we have studied hydrogen chemisorption in single-walled carbon nanotubes. Using atomic hydrogen as the hydrogenation agent, we demonstrated that maximal degree of nanotube hydrogenation depends on the nanotube diameter, and for the diameter values around 2.0 nm nanotube-hydrogen complexes with close to 100% hydrogenation exist and are stable at room temperature. This means that specific carbon nanotubes can have a hydrogen storage capacity of more than 7 wt % through the formation of reversible C-H bonds.     

PEGylated zinc oxide nanoparticles induce apoptosis in pancreatic cancer cells through reactive oxygen species

In this study, the authors have successfully prepared the polyethylene glycol (PEG)‐coated zinc oxide nanoparticles (ZNPs) and studied its effect in pancreatic cancer cells. The authors have observed a nanosized particle with spherical shape. In this study, the authors have demonstrated the cytotoxic effect of ZNP and PZNP in PANC1 cells. To be specific, PZNP was more cytotoxic compared to that of ZNP in PANC1 cancer cells. The authors have further showed that apoptosis is the main mode of cytotoxic activity. It is worth noting that PEGylation of ZNP did not decrease the cell killing activity of zinc particles, whereas it further increases its anticancer effect in the pancreatic cancer cells. The authors have observed a significant upregulation of proapoptotic BAX while expression of antiapoptotic Bcl‐2 was significantly downregulated indicating the potent anticancer effect of zinc nanoparticles. Overall, PEGylation of ZNP could be an effective strategy to improve the stability, while at the same time, its anticancer activity could be enhanced for better therapeutic response.Inspec keywords: biomedical materials, drug delivery systems, tumours, toxicology, nanoparticles, cellular biophysics, drugs, nanomedicine, cancer, nanofabrication, zinc compounds, II‐VI semiconductorsOther keywords: pancreatic cancer cells, reactive oxygen species, polyethylene glycol‐coated zinc oxide nanoparticles, cytotoxic effect, cytotoxic activity, PEGylation, anticancer effect, PEGylated zinc oxide nanoparticle induce apoptosis, proapoptotic BAX upregulation, ZnO     

Dispersion of single-walled carbon nanotubes in aqueous and organic solvents through a polymer wrapping functionalization

The processing and application of single-walled carbon nanotubes (SWNTs) is limited by their purity and dispersion in most common solvents. Non-covalent polymer wrapping functionalization of SWNTs provides an excellent route to improve their property and thus the dispersion in aqueous and organic solvents occurred simultaneously. This paper reports the purification and a methodology for obtaining dispersion of SWNTs, obtained by arc-discharge, using a biocompatible water soluble polymer which, presumably, wraps around nanotubes. Scanning electron microscope (SEM) and high resolution transmission electron microscope (HR-TEM) were employed to examine the dispersion. UV-Vis-NIR spectroscopy further substantiates the presence of dispersed SWNTs in aqueous solution. Raman spectroscopy reveals the impact of chemical and ultrasonic processing on the structural order of the nanotubes. No trace for structural damage has been observed from the Raman studies and so, our treatment is considered as a physical rather chemical process. The polymer treated tubes become more hydrophilic which was confirmed by contact angle measurement.     

Experimental and theoretical studies of transport through large scale, partially aligned arrays of single-walled carbon nanotubes in thin film type transistors

Gate-modulated transport through partially aligned films of single-walled carbon nanotubes (SWNTs) in thin film type transistor structures are studied experimentally and theoretically. Measurements are reported on SWNTs grown by chemical vapor deposition with systematically varying degrees of alignment and coverage in transistors with a range of channel lengths and orientations perpendicular and parallel to the direction of alignment. A first principles stick-percolation-based transport model provides a simple, yet quantitative framework to interpret the sometimes counterintuitive transport parameters measured in these devices. The results highlight, for example, the dramatic influence of small degrees of SWNT misalignment on transistor performance and imply that coverage and alignment are correlated phenomena and therefore should be simultaneously optimized. The transport characteristics reflect heterogeneity in the underlying anisotropic metal-semiconductor stick-percolating network and cannot be reproduced by classical transport models.     

Synthesis of porous,hydrophobic aerogel through the reinforcement of bamboo-shaped oxidized multi-walled carbon nanotubes in the silica matrix for oil spill cleaning

Clean Technologies and Environmental Policy - In the present work, bamboo-shaped Oxidized Multi-walled Carbon Nanotubes (O-MWCNT) synthesized through catalytic decomposition of natural gas were...